The invention relates to a marine fuel system for a fuel injected engine, and more particularly to a system for removing and recirculating fuel puddles including heavy fuel ends from low points in the crankcase.
In two cycle internal combustion engines, at idle speed, heavy fuel ends condense on the walls of the crankcase and accumulate in the lowest part of the crankcase i.e. form fuel puddles. Various systems are known for recirculating the puddled fuel back into the crankcase for subsequent combustion. For example, the puddled fuel in the crankcase of one of the cylinders is pumped out during the combustion power stroke of the piston in that cylinder pressurizing that section of the crankcase, and the puddled fuel is supplied to the crankcase of another cylinder whose piston is in its charging stroke thus creating a vacuum drawing fuel into that section of the crankcase. In other systems, the puddled fuel is recirculated with the fresh incoming fuel.
In fuel injected engines, it is important to accurately control the quantity of fuel delivered to the engine through the fuel injectors. It is common to use a high pressure pump to supply fuel to the injectors with a pressure regulator providing an essentially constant fuel pressure at the injector. Excess fuel, i.e. the amount over and above that required by the engine, is recirculated, usually through a vapor separator, back to the fuel pump.
In the present invention, the returned excess fuel flow from the fuel injectors to the fuel pump is used to create a vacuum for suctioning puddled fuel from the engine crankcase. In preferred form, the puddled fuel return line is connected to the excess fuel return line by a venturi in the latter.